A study of the effects of various vein graft preparation techniques on the morphology, ATP levels, and short and long-term patency rates of coronary artery and peripheral vein bypass grafts (VBG) is proposed. A chief goal of the study will be to avoid excessive smooth muscle cell contraction and bleb formation and to improve endothelial retention. Dog saphenous veins will be harvested and soaked for 5 min. or 1 hr. in one of 8 solutions at 10 degrees C or 20 degrees C. Pre-and post-soak control vein segments will be obtained. Other segments of the same veins will then be inserted as coronary artery and femoral artery bypass grafts which will be harvested at 48 hrs. and 1 mo. Endothelial preservation, microthrombus formation, smooth muscle blebs, etc. will be quantitated and compared pre- and post-soak by scanning electron microscopy. Vein graft post-op patency will be measured by angiography and light and transmission electron microscopy. Quantitative data on the success of VBG preparation techniques will be correlated with subsequent patency rates. In this way improved vein preparation techniques may be developed which will reduce the serious clinical problem of post-op VBG occlusion necessitating reoperation.